Drop bolt snap latch locking mechanism

ABSTRACT

A drop bolt locking combination capable of snap latch operation is provided with a resiliently biased bolt element and cooperating strike member which enables the bolt element to be moved to a withdrawn position and then snapped into locking arrangement with the strike member upon closing of the door. The bolt element has a plurality of fingers having spring biased ball bearings therein while the strike member has beveled flanges thereon for engaging the ball bearings and moving the bolt element a sufficient distance against spring biasing to permit closing of the door without the necessity of withdrawing the bolt element by knob operation.

United States Patent Prahl DROP BOLT SNAP LATCH LOCKING MECHANISMPrimary ExaminerAlbert G. Craig, Jr. [76] Inventor: Herman Prahl, 48-38Fifty Eight Attorney Agent 9 firm-Harvey Zeuer W d 'd ,N.Y. H377 e 57ABSTRACT [22] Flled: June 1973 A drop bolt locking combination capableof snap latch [21] Appl. N0.: 371,141 operation is provided with aresiliently biased bolt element and cooperating strike member whichenables the bolt element to be moved to a withdrawn position tg zg figand then snapped into locking arrangement with the [58] Fie'ld "70/91 976 106 143 strike member upon closing of the door. The bolt ele- 7O/46241562 16 ment has a plurality of fingers having spring biased 157 ballbearings therein while the strike member has bevi eled flanges thereonfor engaging the ball bearings and [56] References Cited moving the boltelement a sufficient distance against spring biasing to permit closingof the door without UNITED STATES PATENTS the necessity of withdrawingthe bolt element by knob 1,253,734 l/l9l8 Sheinman 70/106 operation1,378,504 5 1921 White 1,399J58 12/1921 Segal 70 104 4 ClaImS 5 DrawlngFlgures 96 i 104\\ \1 84x7 l j DROP BOLT SNAP LATCH LOCKING MECHANISMBACKGROUND OF THE INVENTION The present invention relates to drop boltlock mechanisms and particularly to a drop bolt lock mechanism capableof snap latch operation.

In recent years, lock security has become of increasing importance.While numerous improvements have been made in the attempt to devise pickproof locks by modifying the key operated cylinder mechanism, theseimprovements are of little significance where the bolt element may bedisplaced from the outside without the use of a key or the requirementfor rotating the key plug within the cylinder lock. Methods foraccomplishing this are well known. As a result, there has been a resortto drop bolt locks which provide substantial protection against thedisplacement of the bolt element without the use of a key. This,however, in most situations, has required the use of two locks since inmany situations people desire the convenience of having a snap latch foraffording only partial security under circumstances when they are to behome or when they are to be out for only a few minutes or in situationswhen they do not wish to go to the door each time that a visitor withouta key leaves.

It is therefore an object of the present invention to provide a dropbolt lock which is capable of operating in a snap latch fashion therebyavoiding the necessity of the use of two locks while at the same timeincreasing the security provided where the lock is used in the snaplatch fashion.

It is a further object of the present invention to provide such a dropbolt lock which is capable of operating in a snap latch fashion on bothswing open doors and on sliding doors.

SUMMARY OF THE INVENTION The above objects are accomplished by means ofthe present invention which briefly includes a drop bolt lock having aresiliently biased bolt element normally biased in a locking directionand having finger means on the bolt element cooperative with a strikemember to move the bolt element to a retracted position upon closing thedoor to enable snap latch operation. The finger means is of a hollowcylindrical shape and includes a spring within the hollow section and aball bearing projecting therefrom. The strike member is beveled along anedge to engage the ball bearing and lift the bolt element. Beveling ofthe strike member and usage of the ball bearing enables the utilizationof the lock on either swing doors or sliding doors.

BRIEF DESCRIPTION OF DRAWINGS I drop bolt lock and strike member engagedin the snap lock position.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings andparticularly to FIGS. lthrough '3 there is shown a drop bolt lockgenerally designated as 10 in FIG. 1 having its cover removed. The lock10 includes a base plate 12 which may be secured to a door with the edgeof the door being designated 14. The base plate 12 may be secured to thedoor by means of screws 16. The base plate 12 includes an aperturetherein for the operating element 18 which may be secured to the keyplug of a cylinder lock (not shown) or which may be operable by the rodof a rim lock. The base plate 12 also has cut-outs 20 and 22perpendicular to the door edge 14 for cooperation with a strike elementas to be explained hereafter.

Cover 24 is provided for covering the base plate 12 and mechanisminternal thereto. The cover 24 has a peripheral flange 26. On an edge ofthe flange 26 is a projecting tab 28 for mating with the base plate 12under a raised portion 30. At the opposite end of the flange areapertures 32 and 34 for alignment with threaded bores 36 and 38,respectively, in tabs '40 and 42, respectively; of the base plate 12whereby the cover 24 may be secured to the base plate 12 by means ofscrews not shown. The cover 24 may also have an operating element 44mounted therein for rotation of a knob. Cover 24 is provided with spaces46 and 48 for cooperation with a strike element as'to be explainedhereinafter.

The base plate 12 and cover 24 constitute a housing for bolt element 50.The bolt element 50 is operable by either of operating elements 18 and44. The bolt element 50 has a bolt head 52 as shown in FIG. 4. The bolthead 52 is secured between a pair of plates, only one of which is shownas S1. The bolt head 52 includes a pair of cylindrical fingers 54 and 56which extend parallel to door edge 14 and are guided for movement in avertical direction in apertures 58 and 60, respectively, in flange 26.Additionally, guiding the bolt element 50 is a pin 62 on cover 24 whichmates with elongated slot 64 in plate 51 of bolt element 50. Under snaplatch operating conditions pin 62 abuts against the lower edge of tab66. The internal operating mechanism of the bolt element 50 between itsplates is identical to the corresponding structure of applicantscopending US. Application Ser. No. 182,590 filed on Sept. 22, 1971, nowUS. Pat. No. 3,759,074 dated Sept. 18, 1973 and the description thereinis incorporated here by reference.

Also included on the cover 24 is a pin 68 having a torsion spring 70thereon which normally biases the bolt element 50 downwardly. A cutout72 is provided in plate 51 permitting the bolt element 50 to be movedupwardly against the bias of spring 70 for snap latch operation, as tobe explained hereinafter, and permitting further upward movement wherebykeeper 74 may be moved in slot 76 in cover 24 into cutout 78 in boltelement 50 to hold the bolt element 50 in a retracted position wherebyno locking action is provided.

Strike element 80 shown in FIG. 2 consists of a base 82 having a pair ofprojecting flanges 84 and 86. The strike element 80 is mounted on thedoor frame adjacent the edge 88 thereof by screws 90, 92 and 94. Whenthe door is closed the flanges 84 and 86 enter the spaces provided bycutouts 20 and 22 of the base plate 12 and spaces 46 and 48 of the cover24.

Referring now to FIGS. 4 and 5, there is shown the novel bolt head andstrike construction which permit the usage of the drop bolt lock of theinstant invention in a snap latch mode of operationrReferring first tobolt head 52, the cylindrical fingers 54 and 56 are provided withsprings 96 and 98, respectively, and ball bearings 100 and 102,respectively. Referring next to the strike element 80, flanges 84 and 86are provided with bevelled edges 104 and 106.

In mounting the strike element 80 and locking mechanism it is necessaryto arrange these members so that when the bolt element 50 is in the snaplatch position with the tab 66 in engagement with pin 62, the ballbearings 100 and 102 will strike bevelled edges 104 and 106 when thedoor is closed. Furthermore, the bevelled edges 104 and 106 must be ofsufficient height so that when the door is closed and the fingers 54 and56 are within apertures 108 and 110, respectively, the verticalcylindrical surfaces of fingers 54 and 56 must reside within theapertures 108 and 110, respectively.

In operation, when a door having the described locking mechanism isclosed against a door frame having the described strike element, ballbearings 100 and 102 strike bevelled edges 104 and 106, respectively, tomove bolt element 50 upwardly against the biasing of spring 70. Whilethis occurs, ball bearings 100 and 102 also move upwardly against thebiasing of springs 96 and 98, respectively, reducing the necessarymovement of the bolt element 50 thereby reducing the force necessary toclose the door. Additionally, ball bearings 100 and 102 rotate furtherreducing the friction and force necessary. It is noted that sincebevelled edges 104 and 106 extend around flanges 84 and 86, themechanism may be used on either swinging doors or sliding doors. Oncethe door has been closed, cylindrical fingers 54 and 56 reside withincylindrical bores 108 and 110, respectively, and prevent biasing of boltelement 50 upwardly by pushing or pulling on the door and therebyprevent opening the door without utilization of operating elements 18 or44.

The drop locking mechanism described may also be used as a locking boltlock by rotating the operating elements 18 or 44 to move tab 66 to aposition beneath pin 62 in the manner described in the aforementionedcopending application.

While the present invention has been described with respect to anillustrative embodiment thereof, modifications will now become apparentto those of ordinary skill in the art. For instance, while the lockingmechanism has been described whereby the bolt element is guided formovement by elements on the cover 24, it is equally possible to placethe flange 26 and guiding pin 62 on the base plate 12. Furthermore, itis possible to use a different bolt element than that described hereinprovided the same bolt head is used. It is therefore intended that thescope of the invention be determined bythe chains appended hereto.

What is claimed is:

l. A drop bolt locking mechanism and strike member combination capableof snap latch operation comprising:

a bolt element housing for mounting upon a door with a portion of saidhousing extending beyond the edgeof said door, said portion consistingof a plurality of sections with spaces between said sections extendingin a direction substantially perpendicular to said edge of said door;

a bolt element mounted within said housing for movement therein relativeto said housing in a direction substantially parallel to said edge ofsaid door, said bolt element having finger means thereon for movement insaid spaces in a direction parallel to said edge of said door;

means in said housing for resiliently biasing said bolt element in afirst direction parallel to said edge of said door for normallymaintaining said finger means in said spaces; 7

a strike member for mounting on the door frame opposite said housing,said strike member having a plurality of projecting flange means formating with said spaces and said flanges having apertures therein forreceipt of said finger means;

said flange means having bevelled edges for engaging said finger meansand pushing said bolt element in a second direction opposite to saidfirst direction upon closing of said door to enable said snap latchoperation; and

said finger means having ball bearings projecting therefrom into saidspaces to facilitate said snap latch operation.

2. The combination according to claim 1 wherein said finger means arehollow cylindrical extensions of said bolt element and said ballbearings project from their open ends extending into said spaces andmeans within said cylindrical extensions biasing said ball bearings intosaid spaces.

3. The combination according to claim 1 further including means formoving said bolt element to a position wherein said finger means iswithdrawn from said spaces and means for retaining said finger meanswithdrawn from said spaces.

4. The combination according to claim 1 further including means formoving said bolt element to a locking bolt position.

1. A drop bolt locking mechanism and strike member combination capableof snap latch operation comprising: a bolt element housing for mountingupon a door with a portion of said housing extending beyond the edge ofsaid door, said portion consisting of a plurality of sections withspaces between said sections extending in a direction substantiallyperpendicular to said edge of said door; a bolt element mounted withinsaid housing for movement therein relative to said housing in adirection substantially parallel to said edge of said door, said boltelement having finger means thereon for movement in said spaces in adirection parallel to said edge of said door; means in said housing forresiliently biasing said bolt element in a first direction parallel tosaid edge of said door for normally maintaining said finger means insaid spaces; a strike member for mounting on the door frame oppositesaid housing, said strike member having a plurality of projecting flangemeans for mating with said spaces and said flanges having aperturestherein for receipt of said finger means; said flange means havingbevelled edges for engaging said finger means and pushing said boltelement in a second direction opposite to said first direction uponclosing of said door to enable said snap latch operation; and saidfinger means having ball bearings projecting therefrom into said spacesto facilitate said snap latch operation.
 2. The combination according tocLaim 1 wherein said finger means are hollow cylindrical extensions ofsaid bolt element and said ball bearings project from their open endsextending into said spaces and means within said cylindrical extensionsbiasing said ball bearings into said spaces.
 3. The combinationaccording to claim 1 further including means for moving said boltelement to a position wherein said finger means is withdrawn from saidspaces and means for retaining said finger means withdrawn from saidspaces.